Romanes on Weismann.

For this study the examina­tion of Weismannism by Romanes published in 1893 is of great value. I need only refer here to the main conclusions of that lucid and learned examina­tion.

Weismann’s work on the germ-plasm in pursuance of a theory of heredity is pronounced by Romanes to have remained up to 1893 substantially unaltered, though largely added to in matters of detail, and at the present time as far as I gather from a study of the more recent literature this theory holds the field or at least a commanding position in it.[26] Originally he held that the germ-plasm possessed perpetual continuity since the first origin of life, and absolute stability since the first origin of sexual propaga­tion, but he has shown himself willing to surrender the first postulate, and has himself altered the second. As it stands now it must be admitted that the continuity of the germ-plasm is an interrupted continuity with the appearance of every inherited change; the continuity is theoretical, not actual, and the stability of the germ-plasm is not absolute but of a high degree. We can thus see in the story of this original theory of heredity the lighthouse value of the pharos of Ptolemy II.

It is far otherwise with Weismann’s theory of evolution. Romanes shows that with the removal of its essential postulate the absolute stability of germ-plasm, Weismann’s theory of evolution falls to the ground. He has indeed surrendered much in his later building, his second temple of Solomon, and prominent among these was the claim that the only causes of individual variation and of the origin of species in the uni-cellular organisms are the Lamarckian factors, just as in the multicellular the only cause of these is natural selection. Thus we see standing at the critical date, 1892, the first Eddystone lighthouse of Winstanley, a greater and more important structure than the old pharos.